Inherent in the use of medical devices, particularly in the use of devices which are at least in partial contact with body fluids, is the problem of infection. Furthermore, therapeutic uses of collagen, particularly for wound healing, repair of scar tissue, and cosmetic surgery, is becoming increasingly important. The problem with collagen, as with any other substance which is foreign to the body, is how to make these proteinaceous substances substantially sterile and/or inhibitive to infection. The present invention provides a method for producing antibacterial and antifungal collagen for such uses.
The type of collagen to which the present invention is applicable is insoluble, renatured collagen in the form of felts, foams, sponges, and films which are porous. By the term renatured, it is meant that the collagen is not collagen in its natural state, but rather it has been denatured to its triple helix form (often called tropocollagen or procollagen) by treatment of natural collagen with salt solutions, acid solutions and/or denaturing enzymes, then reprecipitated into collagen fibril. The fibrils are held together by bonding forces between the side chains of the amino acid residues of the protein chains, the main bond being hydrogen bonds. The association of fibrils into macromolecules, again by primarily hydrogen bonding, renatures, or reconstitutes, the collagen. The advantage of a renatured collagen is that, particularly in the case when denaturing enzymes are used, the renatured collagen is of much higher purity, being stripped of telopeptides and/or saccharides, thus resulting in collagen which is less antigenic than the naturally-occurring collagen. As used herein, the term renatured collagen also includes collagen which has been reconstituted to reform hydrogen bonding and chemically cross linked using chemical cross linking reagents such as, dialdehydes, diesters, diamines, and the like.
While treatment of some types of collagen with silver nitrate or other silver salts is known in the art (see Fox, et al., Ann. Chir. Plast., Vol. 24 (No. 3) pp. 265-267 (1979); and U.S. Pat. No. 4,294,241), it is believed that it has not been heretofore shown to improve collagen by forming a reconstituted and/or cross linked collagen having improved silver ion retention by treatment of ultraviolet radiation.
It is thus an object of the present invention to provide improved collagen having antibacterial and antifungal properties.
It is yet another object of the present invention to provide medical devices containing collagen on at least one surface thereof which has improved bactericidal and fungicidal properties.
It is yet another object of the present invention to provide topical therapeutic agents comprising collagen having improved antibacterial and antifungal properties.
Other objects and advantages of the present invention will be apparent from a further reading of the following specification and appended claims.